Radar apparatus and method for transmission and reception by radar apparatus

Abstract

In a radar apparatus, either a plurality of transmission antennas or a plurality of reception antennas include a first antenna group disposed in a first direction and a second antenna group disposed in a second direction different from the first direction, and an other of the plurality of transmission antennas and the plurality of reception antennas include a third antenna group disposed in a third direction different from each of the first direction and the second direction.

1 . A radar apparatus, comprising:
 transmission circuitry, which, in operation, transmits a transmission signal using a plurality of transmission antennas; and   reception circuitry, which, in operation, receives a reflected wave signal using a plurality of reception antennas, the reflected wave signal being the transmission signal reflected by an object, wherein   either the plurality of transmission antennas or the plurality of reception antennas include a first antenna group disposed in a first direction and a second antenna group disposed in a second direction different from the first direction, and   an other of the plurality of transmission antennas and the plurality of reception antennas include a third antenna group disposed in a third direction different from each of the first direction and the second direction.   
     
     
         2 . The radar apparatus according to  claim 1 , wherein:
 the radar apparatus is installed in a vehicle, and   the first direction and the second direction are different directions with respect to a vertical direction and a horizontal direction, the vertical direction being a height direction of the vehicle, the horizontal direction being a forward traveling direction of the vehicle and a direction orthogonal to the forward traveling direction of the vehicle.   
     
     
         3 . The radar apparatus according to  claim 1 , wherein
 the first direction and the second direction are different directions with respect to a vertical direction and a horizontal direction, the vertical direction being a gravity direction, the horizontal direction being a direction orthogonal to the gravity direction.   
     
     
         4 . The radar apparatus according to  claim 2 , wherein
 the third direction is a direction coinciding with the horizontal direction.   
     
     
         5 . The radar apparatus according to  claim 1 , wherein
 a minimum spacing between the first antenna group and the second antenna group is greater than an aperture length of the third antenna group.   
     
     
         6 . The radar apparatus according to  claim 1 , wherein
 the first antenna group and the second antenna group include one or more shared antennas.   
     
     
         7 . The radar apparatus according to  claim 1 , wherein
 an antenna arrangement included in the first antenna group and an antenna arrangement included in the second antenna group have line symmetry with respect to a line orthogonal to the third direction.   
     
     
         8 . The radar apparatus according to  claim 2 , wherein:
 a spacing between adjacent antennas of the third antenna group in the horizontal direction is dT×D H ,   a spacing between adjacent antennas included in the first antenna group in the horizontal direction is dRH 1 ×D H ,   a spacing between adjacent antennas included in the first antenna group in the vertical direction is dRV×D V ,   a spacing between adjacent antennas included in the second antenna group in the horizontal direction is dRH 2 ×D H ,   a spacing between adjacent antennas included in the second antenna group in the vertical direction is dRV×D V ,   the D H  and the D V  are values in a range of 0.45 to 0.8 times the wavelength of the transmission signal, and   the dT is a value equal to or greater than 2, each of the dRH 1  and the dRH 2  is a value equal to or greater than 1.   
     
     
         9 . The radar apparatus according to  claim 1 , wherein
 a spacing between adjacent antennas is an equal spacing in each of the third antenna group, the first antenna group, and the second antenna group.   
     
     
         10 . The radar apparatus according to  claim 1 , wherein
 a spacing between adjacent antennas includes one or more unequal spacings in at least one of the third antenna group, the first antenna group, and the second antenna group.   
     
     
         11 . The radar apparatus according to  claim 1 , wherein
 the third antenna group includes a plurality of sets of at least some antennas arranged in the third direction.   
     
     
         12 . The radar apparatus according to  claim 1 , wherein
 the either the plurality of transmission antennas or the plurality of reception antennas include a plurality of the first antenna groups and a plurality of the second antenna groups.   
     
     
         13 . The radar apparatus according to  claim 1 , wherein
 the plurality of transmission antennas include two types of antenna elements differing at least in size.   
     
     
         14 . The radar apparatus according to  claim 1 , wherein
 the other of the plurality of transmission antennas and the plurality of reception antennas include a fourth antenna group disposed in a fourth direction different from the third direction.   
     
     
         15 . The radar apparatus according to  claim 2 , wherein:
 the other of the plurality of transmission antennas and the plurality of reception antennas include a fourth antenna group disposed in a fourth direction different from the third direction, and   the third direction and the fourth direction are different directions with respect to the horizontal direction and the vertical direction.   
     
     
         16 . The radar apparatus according to  claim 14 , wherein
 the first direction, the second direction, the third direction, and the fourth direction are different from one another.   
     
     
         17 . The radar apparatus according to  claim 14 , wherein
 the third antenna group and the fourth antenna group include one or more shared antennas.   
     
     
         18 . The radar apparatus according to  claim 15 , wherein:
 a spacing between adjacent antennas of the third antenna group in the horizontal direction is dTH 1 ×D H ,   a spacing between adjacent antennas included in the third antenna group in the vertical direction is dTV 1 ×D V ,   a spacing between adjacent antennas of the fourth antenna group in the horizontal direction is dTH 2 ×D H ,   a spacing between adjacent antennas included in the fourth antenna group in the vertical direction is dTV 2 ×D V ,   a spacing between adjacent antennas included in the first antenna group in the horizontal direction is dRH 1 ×D H ,   a spacing between adjacent antennas included in the first antenna group in the vertical direction is dRV 1 ×D V ,   a spacing between adjacent antennas included in the second antenna group in the horizontal direction is dRH 2 ×D H ,   a spacing between adjacent antennas included in the second antenna group in the vertical direction is dRV 2 ×D V ,   the D H  and the D V  are values in a range of 0.45 to 0.8 times the wavelength of the transmission signal, and   each of the dTH 1 , the dTV 1 , the dTH 2 , the dTV 2 , the dRH 1 , the dRV 1 , the dRH 2 , and the dRV 2  is a value equal to or greater than 1.   
     
     
         19 . The radar apparatus according to  claim 1 , wherein:
 the other of the plurality of transmission antennas and the plurality of reception antennas further include a fourth antenna group disposed in a fourth direction different from the third direction,   the third direction is a same direction as the first direction, and   the fourth direction is a same direction as the second direction.   
     
     
         20 . The radar apparatus according to  claim 1 , wherein
 a spacing between adjacent antennas in the third antenna group is equal to or greater than one wavelength of the transmission signal.   
     
     
         21 . A method for transmitting and receiving a radar signal, comprising:
 transmitting a transmission signal using a plurality of transmission antennas; and   receiving a reflected wave signal using a plurality of reception antennas, the reflected wave signal being the transmission signal reflected by an object, wherein   either the plurality of transmission antennas or the plurality of reception antennas include a first antenna group disposed in a first direction and a second antenna group disposed in a second direction different from the first direction, and   an other of the plurality of transmission antennas and the plurality of reception antennas include a third antenna group disposed in a third direction different from each of the first direction and the second direction.